Electrophotography is a useful process for printing images on a receiver (or “imaging substrate”), such as a piece or sheet of paper or another planar medium, glass, fabric, metal, or other objects as will be described below. In this process, an electrostatic latent image is formed on a photoreceptor by uniformly charging the photoreceptor and then discharging selected areas of the uniform charge to yield an electrostatic charge pattern corresponding to the desired image (a “latent image”).
After the latent image is formed, charged toner particles are brought into the vicinity of the photoreceptor and are attracted to the latent image to develop the latent image into a visible image. Note that the visible image may not be visible to the naked eye depending on the composition of the toner particles (e.g., clear toner).
After the latent image is developed into a visible image on the photoreceptor, a suitable receiver is brought into juxtaposition with the visible image. A suitable electric field is applied to transfer the toner particles of the visible image to the receiver to form the desired print image on the receiver. The imaging process is typically repeated many times with reusable photoreceptors.
The receiver is then removed from its operative association with the photoreceptor and subjected to heat or pressure to permanently fix (“fuse”) the print image to the receiver. Plural print images, e.g., of separations of different colors, are overlaid on one receiver before fusing to form a multi-color print image on the receiver.
FIG. 2 shows an embodiment of a development station for bringing toner particles into the vicinity of the photoreceptor. Belt photoreceptor 25 is adjacent to development station 23, which includes toning roller 210, feed roller 220, and sump 230. Sump 230 contains developer 235 including toner particles. Feed roller 220 includes protrusions 225 for carrying developer from sump 230 to toning roller 210. Metering skive 214 is spaced apart from toning roller 210 to permit an appropriate amount of developer to pass to toning zone 217, in which toner is transported to photoreceptor 25. Mixer 237 rotates to tribocharge and mix developer 235. An example of a system using a feed roller is given in U.S. Pat. No. 7,792,467.
Other printers using feed rollers are various models in the KODAK DIGIMASTER EX series, such as the EX 110. This printer uses a ribbon blender to provide toner to the toning roller. The ribbon blender has two paddles, each about five inches long, that are set 180° around the blender from each other.